102 lines
		
	
	
		
			2.0 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			102 lines
		
	
	
		
			2.0 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
package core
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import (
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	"sync"
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	"github.com/ethereum/go-ethereum/common"
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	"github.com/ethereum/go-ethereum/core/types"
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)
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// BlockCache implements a caching mechanism specifically for blocks and uses FILO to pop
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type BlockCache struct {
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	size int
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	hashes []common.Hash
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	blocks map[common.Hash]*types.Block
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	mu sync.RWMutex
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}
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// Creates and returns a `BlockCache` with `size`. If `size` is smaller than 1 it will panic
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func NewBlockCache(size int) *BlockCache {
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	if size < 1 {
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		panic("block cache size not allowed to be smaller than 1")
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	}
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	bc := &BlockCache{size: size}
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	bc.Clear()
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	return bc
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}
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func (bc *BlockCache) Clear() {
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	bc.blocks = make(map[common.Hash]*types.Block)
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	bc.hashes = nil
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}
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func (bc *BlockCache) Push(block *types.Block) {
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	bc.mu.Lock()
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	defer bc.mu.Unlock()
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	if len(bc.hashes) == bc.size {
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		delete(bc.blocks, bc.hashes[0])
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		// XXX There are a few other options on solving this
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		// 1) use a poller / GC like mechanism to clean up untracked objects
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		// 2) copy as below
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		// re-use the slice and remove the reference to bc.hashes[0]
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		// this will allow the element to be garbage collected.
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		copy(bc.hashes, bc.hashes[1:])
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	} else {
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		bc.hashes = append(bc.hashes, common.Hash{})
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	}
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	hash := block.Hash()
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	bc.blocks[hash] = block
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	bc.hashes[len(bc.hashes)-1] = hash
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}
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func (bc *BlockCache) Delete(hash common.Hash) {
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	bc.mu.Lock()
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	defer bc.mu.Unlock()
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	if _, ok := bc.blocks[hash]; ok {
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		delete(bc.blocks, hash)
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		for i, h := range bc.hashes {
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			if hash == h {
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				bc.hashes = bc.hashes[:i+copy(bc.hashes[i:], bc.hashes[i+1:])]
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				// or ? => bc.hashes = append(bc.hashes[:i], bc.hashes[i+1]...)
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				break
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			}
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		}
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	}
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}
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func (bc *BlockCache) Get(hash common.Hash) *types.Block {
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	bc.mu.RLock()
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	defer bc.mu.RUnlock()
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	if block, haz := bc.blocks[hash]; haz {
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		return block
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	}
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	return nil
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}
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func (bc *BlockCache) Has(hash common.Hash) bool {
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	_, ok := bc.blocks[hash]
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	return ok
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}
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func (bc *BlockCache) Each(cb func(int, *types.Block)) {
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	bc.mu.Lock()
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	defer bc.mu.Unlock()
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	i := 0
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	for _, block := range bc.blocks {
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		cb(i, block)
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		i++
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	}
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}
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